I just got my diff cover in today which i believe will hold 8 quarts for the 11.5 rear end. As much as I wanna use amsoil, i need something cheaper. I plan on putting around 10,000 miles a month and changing my fluid every 10,000 to 20,000 miles. I want to keep my maintance down to a mininum cost but I dont want to put cheap crap in either. My rear end does have a limited slip from factory and my rear end is getting abused really bad from a 20,000 pound load, CONSTANTLY!!!!!!!! Yes im a hotshotter. Which brand and which wieght of diff fluid should i use as tonight im changing my cover and pouring in the new fluid. I have just hit 3000 miles.

Also, If you would like to leave comments on oil for engine to that would be appreciated as that is next to change this week!!!!!! Thanks guys for all your help as Im new to the cummin world. My ford is going bye bye today as it got sold for 26,000 dollars to a dealership in houston last night. Im signing title over as I write this topic.

P.S. My ford only hit the shop once as it had a bad egr. But I got a full carbon cleaning and new turbo for 100 bucks!!!

 

Considering what you will be using your truck for, I'd go with a 75W-140 synthetic gear oil. IMO, Red Line 75W-140 is the best gear oil made. Changing a synthetic gear oil at anything less than 30K miles is a waste of money.

As far as engine oil....being that you have a 6.7 you MUST use a CJ4 spec HDEO. There is no difference in engine wear with a syn -vs- a dino oil (as confirmed by thousands upon thousands of UOA's). You live in Florida, so cold weather pumpability isn't a concern. With that said, I'd run Delo 400 15W-40 and enjoy many trouble free miles.

Something else to consider....being as you put a lot of miles on your truck. I'd HIGHLY recommend bypass oil filtration. It will allow you to go on longer OCI's (oil change intervals) because it keeps your oil clean. Remember, oil doesn't wear out. It gets dirty, which forces the oil to use it's additive package and thereby exhausting itself of what protects your engine from wear. Bypass filtration will keep your additive package fighting longer, hence protecting your engine longer. Good luck with the truck.

 

Thanks for the quick response! I lived in houston for 4 years but now im back in good ole clearwater florida where the heat is about the same, minus 5 degrees. I like my new cover for the ease of change of fluid and the dipstick feature, plus cool looks and the stuff that it does for durability. I wasnt gonna plan on changing diff fluid till it started to brown. If it took 40k miles, i wouldnt do it till then, but my truck has only 3k at the time so its ready for its first plus, u know the switch i have no choice. I think im gonna order a bypass, i seen them before on peoples sigs but i thought they are just to make oil changes easier. Shows what I know. I always used Rotella T in my ford, is that the same as what your talking about??????

 

Rotella T and Delo are both popular 15W-40 HDEO's. Two different brands.

Delo has the better add pack as compared to Rotella IMO and has shown lower wear (especially iron) in the boat load of UOA's that I've seen.

 

For my 6.7 I've been using the Rotella Triple Protection that's
suppose to be formulated for the new 07 motors. It's
the low ash or ultral low ash oil designed for these engines.

I'm not sure if it's the best but until I'm sold on something else I think
the New Rotella Triple is good. I change my oil every 5k-7k miles. It's cheap
at Walmart for about $9 a gallon. I have a little over 59,000 miles
on my 6.7 since March with no problems.

Good luck with your new truck.

 

If your not going to change diff fluids until it begins to Brown then AMSOIL is certainly NOT to expensive. They sai it can go 100,000 severe service! If your a prefered customer it's about 9.00 a quart I believe. It's 20.00 to become a prefered customer... Well worth your money!

 

If you are going to use regular oil then IMHO Chevron Delo 400 is the better oil to use. BTW, if you only plan on changing your gear oil when it gets dark then you may be better off using Amsoil severe gear oil as I think it will hold up longer. BTW, If you want extra long drain intervals look at Amsoil 80w140 Long Life gear oil as they say it will hold up in OTR trucks for up to 500,000 miles. If you go with Amsoil then pay the $20.00 to be a preferred member so you can by your oil at dealer cost.

 

Well, i just ordered 8 quarts of amsoil severe svo 75/140 with preferred member and shipping cost 120 bucks. That should last every 50k miles. Thanks for your input. Oil change comes next!!!!!!!! Gosh, i got almost 400 buks wrapped up in my rear end already!!! This work vehilce is expensive.

 

All I can say is WOW!!!!!!!!!!!!!
My diff oil came out dark dark brown/black. Let alone only 3 1/2 quarts came out while 8 quarts went in with my new diff cover!!!!!!!!!!